Electrodynamic speaker unit



Dec. 24, 1935. H N, ROWE 2,025,127

ELECTRODYNAMIC SPEAKER UNIT Filed Sept. 1, 1934 amen ion Horace N. Rowedam- M:

Patented Dec. 24, 1935 UNITED STATES ELECTRODYNAMIC SPEAKER UNIT HoraceN. Rowe, Toledo, Ohio, assignor to Fox Sound Equipment Corporation,Toledo, Ohio, a

corporation of Ohio Application September 1, 1934, Serial No. 742,426

3 Claims.

This invention relates to acoustic devices, such asloud speakers, usedfor public address systems, either out-of-doors or indoors, but moreparticularly to the unit containing the electrody namic diaphragm.

Heretofore, much trouble and annoyance has been caused by loud speakerunits of the above character, since the diaphragm not infrequentlyrequires replacement, repair or adjustment, and since this part has beenfixedly secured in the housing, that for repair, adjustment orreplacement to be made, it not only requires disassembly of practicallythe entire unit, but also necessitates removal of the horn. This notonlytakes considerable time and efiort, but requires the services of aperson skilled in the intricacies of the particular mechanism andrenders the speaking system entirely useless temporarily.

An object of this invention is to overcome the above difliculties andproduce a simple and efficient speaker unit having the new and improvedfeatures of.construction, arrangement and operation hereinafterdescribed.

The invention is shown by way of illustration in the accompanyingdrawing, in which:

Figure 1 is a side elevational view partly in section of the inventionas applied to an electrodynamic speaker;

Figure 2 is a rear end view of the device shown in Figure 1 with thehead removed;

Figure 3 is an inside View of the head; and

Figure 4 is a sectional View on the line 4-4 of Figure 3.

The illustrated embodiment of the invention comprises an electrodynamicdevice in the form of a loud speaker unit having a casing IU of steel orother suitable material, in which is disposed a coil II, the ends ofwhich are connected to binding posts I2 and I3 respectively. Disposedcentrally of the casing l0 and within the coil II is a metallic tube l4providing a pole piece, the opposite ends of which are open, one end l5projecting outside of the casing [0 being retained in place by acoupling [5* of zinc die cast or other suitable non-magnetic material,and having screw threads IE to receive a horn I1. Formed in the outerend portion of the tube I4 is an annular groove M in such position as toconcentrate the magnetic flux in close juxtaposition to the diaphragm I8. Cooperating with the opposite end of the tube [4 is a diaphragm I8 ofthe well known piston type having a coil attached thereon which ismovable in a magnetic field. The ends of the coil [9 are attached tobinding posts 20 on the head 2|. Secured to the head 2| by screws 22 isan annular outwardly projecting cap 22 of brass, or other non-magneticmaterial, the outer end of which is closed, the cap being knurled at 23to enable the head to be grasped readily for attaching or detaching thesame to or from the housing II].

It will be noted that the head 2| is recessed at 24 to receive the outeredge portion of the vibratory diaphragm 18 on which are mounted a seriesof insulated rings or washers 25 held in place by screws 26 which alsohold an outer ring 21 in place. The diaphragm I 8 comprises a stiffdish-shaped piston portion l8 and a flexible corrugated portion I8 and aflat edge portion which is held in clamped. relation. In rear of thepiston portion is provided an air chamber- Within the cap 22 againstwhich the piston portion operates, as will be readily understood.

The ring 2'! is provided with a pair of diametrically opposed springfingers 28 at the outer edge thereof, which are adapted to register withnotches 29 in the rim of the housing It]. It is apparent that by placingthe fingers 28 in registry with the notches 29 the head 2| may be movedinto engagement with the housing l0. Thereafter by turning the head 2|the fingers 28 are forced beneath flanges 30, which project inwardlyfrom the casing, as shown on Figure 2, thereby establishing satisfactoryfrictional engagement to retain the parts in assembled relation with thepiston portion 18 of the diaphragm disposed directly in rear of the openend of the tube l4.

The inner edge portion of the ring 21 is embossed or pressed outwardly,as indicated at 3|, and this portion is adapted to be forced intoengagement with a ring 32 of felt, or other suitable compressiblematerial, which surrounds the tube 14 and rests against the coil ll,thereby holding the parts securely and satisfactorily in place.

Details of description of the construction and operation of theelectrodynamic speaker, such as the piston diaphragm, coil, etc., is notgiven because the same are well known to those skilled in this art. Acardinal feature of this invention resides in mounting the diaphragm atone end of the casing and providing a sound passage from the diaphragmto the opposite end of the casing where a horn may be suitably mounted.This enables the diaphragm to be readily and conveniently removed fromthe casing when in need of repair, replacement, or adjustment, bysubstituting another mounting or head containing a diaphragm which hasbeen tested in the shop and is ready for service. Thus, with a minimumamount of time and effort, the speaker can be conditioned for use.

In another aspect, this invention provides an electrodynamic device inwhich the diaphragm is carried by a detachable mounting which can bereadily mounted or detached from the casing, the casing carrying acentrally disposed tube providinga sound passage therethrough andarranged to cooperate for this purpose with the diaphragm. At theopposite end of the casing and in communication with such sound passage,a horn can be conveniently mounted. It is, therefore, apparent that theinvention is not limited to the particular features of construction,operation and arrangement above described, but numerous changes may bemade from a standpoint of design, arrangement and operation withoutdeparting from the spirit of the invention, especially as defined in theappended claims.

What I claim as new and desire to secure by Letters Patent is:

1; In an electrodynamic speaker having a casing enclosed coil and avibratory diaphragm, a head adapted to close one end of the casing,means for mounting said diaphragm on said head, a cap carried by saidhead and extending outwardly therefrom in the rear of said diaphragm toform an air chamber therefor, fingers carried by said head, a flangedisposed on said casing having slots therein to receive said fingerswhereby rotation of said head causes said fingers to engage said flangein a detachable connection, and a'tube extending through said casing foremitting sound from the opposite end thereof.

2. In an electrodynamic speaker having a casing enclosed coil and avibratory diaphragm, a head adapted to close one end of the casing,means for mounting said diaphragm on said head, a cap carried by saidhead and extending outwardly therefrom in the rear of said diaphragm toform an air chamber therefor, a ring carried by said head and having itsinner periphery pressed inwardly, spring fingers formed from said ring,a flange disposed on said casing and having slots therein to receivesaid fingers whereby rotation of said head causes said fingers to movebehind said flange in a detachable connection, a resilient body offibrous material carried by said casing and adapted to abut the inwardlypressed area of said ring when said head is positioned on said casing,and a tube extending through said casing for emitting sound therefrom.

3. In an electrodynamic speaker having a. cas- 15 ing enclosed coil anda vibratory diaphragm, a head adapted to close one end of the casing,means for mounting said diaphragm on said head, a cap carried by saidhead and extending outwardly therefrom in the rear of said diaphragm toform an air chamber therefor, a ring carried by said head and having itsinner periphery pressed inwardly, spring fingers formed from said ring,a flange disposed on said casing and having-slots therein to receivesaid fingers whereby rotation of said head causes said fingers to movebehind said flange in a detachable connection, a resilient body offibrous material carried by said casing and adapted'to abut the inwardlypressed area of said ring When said head is positioned on said casing, atubular pole piece carried centrally of said casing and projecting fromthe end thereof opposite to said head, and a horn detachably connectedto said pole piece.

HORACE N. ROWE.

